1. Field of the Invention
Embodiments of the present invention relate to the field of satellite positioning systems. More particularly, embodiments of the present invention relate generally to a method and system for geofencing mobile transmissions.
2. Related Art
Low-band VHF frequencies that have previously been reserved for applications such as paging have seen a declining utilization as the demand for increased data rate has caused users to migrate to higher frequencies. However, these higher frequencies are becoming increasingly congested, limiting the areas and times in which data transfer can be made.
The Federal Communications Commission (FCC) grants licenses for the transmission of signals. Authorization by the FCC grants stations to operate in accordance with the rules under the provisions of United States, Title 47 of the Federal Code of Regulations (CFR). Title 47 CFR provides the requirements and conditions for commercial mobile radio service providers. In part, 47 CFR provides regulations applicable to paging at low-band VHF.
There are two classes of paging transmitters. A first class system is based on geographic areas such as Basic Economic Areas (BEAs). The second class system is based on fixed sites. Prior Art FIG. 1 illustrates a map 100 showing both a BEA class system and a fixed site class system for a geographic area defined by southern California. As shown in Prior Art FIG. 1, a BEA 110 is outlined to include San Diego County, Orange County, and the regions near the border of California and Arizona. Also, a BEA 120 is outlined north of BEA 110 to include the cities of Los Angeles, Long Beach, San Bernardino, and Riverside. In addition, Prior Art FIG. 1 illustrates a fixed site class system. Carved out of the BEA 120 is a service area 130 centered at a fixed site transmitter near Long Beach.
In both the BEA class system and the fixed site class system, the holder of their respective FCC license has protection from interference caused by others. For example, the holder of the FCC license is authorized with the exclusive right to establish and expand multiple static stations throughout a paging geographic area (e.g., a BEA or a service area). As such, the holder of the FCC license can transmit on a specified channel allocated for assignment in the paging geographic area. This transmission is granted subject to the conditions that no interference may be caused to existing cochannel stations operated by other licensees within the paging geographic area. Further, no interference may be caused to existing or proposed cochannel stations of other licensees in adjoining paging geographic areas.
In the fixed site system, each transmitter has a service area and at a further distance from the antenna, an interference area. As shown in Prior Art FIG. 1, the dotted circle about the site near Long Beach outlines the service area 130 for that transmitter. The FCC rules state that other transmitters, including mobile transmitters, on the same frequency cannot have their interference contours inside the service contour of the licensed transmitter associated with the service area 130.
In the geographic based system, the holder or owner of the FCC license for a BEA can place transmitters anywhere within the BEA provided the interfering contours do not extend into the service areas of existing site licenses or adjacent BEAs. As shown in Prior Art FIG. 1, the BEA 120 outlines a geographic area within which there cannot exist interference contours from other transmitters, including mobile transmitters, operating on the same licensed frequency granted for broadcast within the BEA 120.
As a result, conventional application of the FCC rules for paging broadcasts provides for non-interference of paging signals over a specific licensed channel within a geographic BEA or service area.
A mobile paging transmitter falls under the BEA category. Mobile transmitters have application for enhancing coverage in critical areas where the current fixed pager transmitters provide insufficient coverage, or in the case where a fixed transmitter suffers an outage and service can be restored by use of a mobile transmitter.
Mobile transmitters thus have the capability for being located wherever needed, and therefore also have the capability for causing interference to paging systems in adjacent service areas. Thus there is a need for being able to ascertain their interference potential and to be able to implement corrective action to prevent such interference.